Yesterday, I made my first Linux Journal Blog post about the .Net Ruby announcement and I asked about how this and other similar projects could help each other instead of duplicating each others work. Two Jruby core developers (Charles O. Nutter and Thomas E Enebo) gave me some pretty good feedback.
Charles' feedback went further than he thought though. He's currently got a post up on his blog about getting Mongrel ported to JRuby (it needs to be ported because there are ~1400 lines of C that will need to reimplemented in Java). Zed Shaw, the author of Mongrel, has dropped some comments there.
It looks like there's a good interchange of ideas flowing between the developers from the two projects. We need more cooperation like this.